The ability to align liquid crystalline (“LC”) molecules homogeneously by various surfaces is an important factor determining their use in a variety of applications. For decades, research into liquid crystals and alignment of their molecules has primarily focused on visible spectrum applications, like displays. These applications typically employ transparent liquid crystalline optical elements driven by an external electric field.
Recently, non-visible-spectrum liquid crystal applications have begun to attract attention. Illustrative applications of this type include liquid crystalline tunable microwave devices, such as phased array antennas, tunable capacitors, phase shifters, delay lines, and others. Microwave and infrared liquid crystal devices operate using cells bounded by metallic surfaces (copper, silver, and gold). This is in distinct contrast to optical devices that exploit transparent surfaces, such as indium tin oxide (ITO) glasses and transparent polyimides. Research into and development of these non-visible-spectrum liquid crystal applications has tended to be confined to a relatively small number of companies and universities.